Fix directory for library installation

On CentOS 7 64 bit installations as default libraries will be installed
into the directory lib64. With this change the installation will be done to
the lib directory as on all other operating systems.

CMakeLists.txt

@@ -42,6 +42,8 @@ set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/modules" ${CMAKE_MODULE_PATH})
 #set(CMAKE_PREFIX_PATH "$ENV{SIMPATH}/share/cmake/ZeroMQ" ${CMAKE_PREFIX_PATH})
 set(CMAKE_PREFIX_PATH $ENV{SIMPATH} ${CMAKE_PREFIX_PATH})
 
+set(CMAKE_INSTALL_LIBDIR lib)
+
 # Check if the compiler support specific C++11 features
 # Up to now this is only a check since the code does not use
 # any of the features of the new standard

external/InstallGtest.cmake

@@ -32,6 +32,7 @@ ExternalProject_Add(GTEST
              -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
              -DCMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}
              -DCMAKE_INSTALL_PREFIX=${CMAKE_BINARY_DIR}
+             -DCMAKE_INSTALL_LIBDIR=${CMAKE_INSTALL_LIBDIR}
   INSTALL_COMMAND ${CMAKE_COMMAND} --build . --target install
 )